CS IRGASON, Instruction Manual

Page: 31 / 74

IRGASON
®
Integrated CO
2
/H
2
O Open-Path Gas Analyzer and 3D Sonic Anemometer
19
The algorithm uses the internal heaters to maintain a temperature that is a
couple of degrees above the ambient dewpoint (or frost point) to prevent
condensation and icing from forming on the surface of the optical windows.
The heater control will be disabled under any of the following conditions:
•
Temperature of the detector housing is outside the
−
35 to 55 °C range
•
Temperature of the source housing exceeds 40 °C
• Ambient temperature is outside the − 35 to 55 °C range
•
The supply voltage is below 10 V
The algorithm uses the following environmental parameters to control the
heater:
•
Analyzer body temperature, measured inside the source housing
(heater control does not allow the body temperature to drop below
ambient air temperature)
• Ambient relative humidity (in humidity greater than 80% heaters will
try to maintain internal temperature 2 degrees warmer than ambient)
•
CO
2
signal level (1 min average CO
2
signal level; below 0.7 will
cause the heater to turn on maximum power until the signals recover)
• Average slope of the CO
2
signal level over 1 min
•
Standard deviation of the CO
2
signal over 1 min
When enabled, this setting applies a voltage between 0 and 4500 mV to heaters
near the optical windows of the analyzer. Heated windows inhibit the
formation of condensation, such as dew and frost, and help the analyzer
recover more quickly when precipitation has blocked the optical path. Use this
setting with caution. Excessive heating may lead to density fluctuations and
subsequent flux measurement errors. More information about heater control,
and specifically using a datalogger for control, may be found at the end of
Section 10.2 , EC100Configure()
Instruction
(p. 37)
.
7.14 ECMon
Settings for the IRGASON are easily verified or changed using the Windows
PC support software ECMon ( E ddy C ovariance Mon itor), which is found on
the IRGASON, EC150 & EC155 Support CD (pn 27007) or at
www.campbellsci.com
.
Before installing ECMon , read the file titled _Read_me.txt found on the
IRGASON, EC150 & EC155 Support CD . This file directs the user to install
USB drivers (also found on the support CD), which are required for
communications between the PC and the EC100 via the EC100 USB cable (pn
26563). Some newer PC operating systems will automatically find and
download the USB drivers from the internet when the USB cable is connected
to the PC. Once the drivers are installed, download and run the ECMon.exe
install file. Launch
ECMon
, and connect the EC100 electronics to the PC with
the included EC100 USB cable (pn 26563). The USB connection for the
EC100 electronics is found on the base of the enclosure (see FIGURE 6-7 ).
Once connected, select the appropriate communications port in the ECMon
main page and click Connect (see FIGURE 7-1 ). Next, click on the Setup
button. All of the preceding settings are now available for editing (see FIGURE
7-2 ).